<!DOCTYPE html>
<!-- nested_lists.html
     An example to illustrate nested lists
     -->
<html lang = "en">
  <head> 
    <title> Nested lists </title>
    <meta charset = "utf-8" />
  </head>
  <body>
    <h3> Aircraft Types </h3>
    <ol>
      <li> General Aviation (piston-driven engines) 
        <ol>
          <li> Single-Engine Aircraft 
            <ol>
              <li> Tail wheel </li>
              <li> Tricycle </li>
            </ol> <br />
          </li>
          <li> Dual-Engine Aircraft
            <ol>
              <li> Wing-mounted engines </li>
              <li> Push-pull fuselage-mounted engines </li>
            </ol>
          </li>
        </ol> <br />
      </li>
      <li> Commercial Aviation (jet engines)
        <ol>
          <li> Dual-Engine
            <ol>
              <li> Wing-mounted engines </li>
              <li> Fuselage-mounted engines </li>
            </ol> <br />
          </li>
          <li> Tri-Engine
            <ol>
              <li> Third engine in vertical stabilizer </li>
              <li> Third engine in fuselage </li>
            </ol>
          </li>
        </ol>
      </li>
    </ol>
  </body>
</html>
